The demand for dark chocolate having a high cocoa content has increased greatly internationally in recent years. Scientific studies in which it has been found that the consumption of dark chocolate protects the cardiovascular system may have contributed to bitter chocolates and refined bitter chocolates, that is to say dark chocolates having high cocoa fractions of greater than 70 to up to 99% by weight being consumed more often.
However, dark chocolate is not experiencing increasing popularity only owing to its high content of antioxidants, such as, for example flavonoids such as epicatechin, but especially because of its intense flavour. Gourmets also value single-variety chocolates, in addition to a high cocoa content. Such chocolates are distinguished in that they are produced from cocoa beans of individual noble cocoa varieties such as, for example, the Criollo or Arriba varieties which are native to Central and South America. Since, as in the cultivation of cocoa, as in viticulture, the position of the cultivation areas has a decisive effect on the quality of the cocoa beans, the single-variety chocolates are preferably produced from beans of known cultivation areas and provenances. A connoisseur who prizes the intense richness of aroma of a noble Arriba cocoa, will prefer a chocolate which originates from beans from the low-lying tropical coastal area of Ecuador. If a chocolate having a milder character is wanted, then, for example cocoa from Madagascar, preferably from the northwest island region Sambirano will be selected, which guarantees a balanced, fruity mild character of the chocolate.
For the understanding of the present invention, it is critical to know the traditional production processes for chocolate. An introduction thereto may be obtained, for example, from the pamphlet Chocologie der Chocosuisse, Münzgraben 6, CH 3000 Bern, of 2001. Therefore, hereinafter, only the essential steps in chocolate production will be briefly considered.
Various cocoa varieties and provenances are blended according to company-specific, and frequently highly secret, recipes from the individual manufacturers. The blending ratios have critical effects on the flavour of the respective chocolate.
The shells are removed from the beans and the beans are broken into medium-size pieces, called nibs. The shells are separated from the cocoa nibs by sieving and suction. In the subsequent roasting, primary refining and intensification of the aroma of the broken cocoa beans is sought.
In the subsequent grinding, the coarse nibs are comminuted in mills and ground to a fine cocoa mass. Known mills are fly cutter and ball mills. By means of the heat formed during grinding and as a result of the mechanical disruption of the fat-containing plant cells, the fat proportion contained in the cocoa beans, called cocoa butter, is released and the cocoa mass liquefies. Depending on cocoa variety, the fraction of cocoa butter present in the beans, the melting range of which is approximately 30 to 37° C., is about 50 to 55% by weight, in exceptional cases up to 56% by weight. Provenance plays an important role in the fat content, wherein customarily for beans of the main harvest fat contents of 51 to 53% by weight can be counted upon.
The cocoa mass formed on grinding is a dark thick mass which solidifies on cooling to room temperature. The Dutch chemist Coenraad van Houten applied as early as 1828 for a patent for a hydraulic press for defatting cocoa mass. The cocoa butter fraction of the liquid cocoa mass was able to be reduced thereby to about 27 to 28%. Today, the fat proportion of the cocoa mass, that is to say the cocoa butter, is customarily pressed off in high-performance presses at temperatures of 80° C. and 90° C. and a pressure of 500 bar. The defatted press cake must subsequently be ground in a further processing step to give cocoa powder. The press cake routinely contains a fat proportion of 10 to 12%, or of 20 to 22%. In order that it still may be able to be processed to powder, it must have a maximum fat content of 30%. The liquid fraction which is expressed, that is to say the cocoa butter, is principally used for producing chocolate, but can also be used in cosmetics and pharmaceutical products.
For producing the cocoa butter and the cocoa powder, some of the cocoa mass is fed to hydraulic high-performance presses which, at temperatures of 80° C. to 90° C., and a pressure of 500 bar, reduce the fat content in the cocoa mass to 10 to 22% by weight (hereinafter, all percentages are taken to mean percent by weight, unless explicitly stated otherwise). When the cocoa butter is expressed from the cocoa mass, what is termed “cocoa cake” is formed, almost as a by-product, the fat content of which after pressing varies between 10 and 22%. Alternatively to the known pressing processes, it was proposed in DE 102 53 810 to remove the cocoa butter from finely ground cocoa mass by means of centrifugation and thereby to improve the yield of cocoa butter, that is to say to reduce the fat content of the cocoa powder. Other processes for producing highly defatted cocoa powder are known from US 2006/0198932. Here, it is proposed to process cocoa mass in a continuous extraction process using solvents to give cocoa powder having a fat content of down to below 0.5% by weight. The organic solvents are mixed with the cocoa mass in a tank with supply of heat, and subsequently the solid and liquid phases of the low-viscosity suspension are separated from one another in a horizontal decanter centrifuge. The solid phase or powder phase obtained in this manner is heated further with organic solvent in a second step and fed a second time to the centrifuge. From the solid phase of the second extraction step, the organic solvent must then again be evaporated off. The liquid fractions of cocoa butter and solvent must likewise be post-treated in order to remove the solvent.
The high amount of effort required to obtain the cocoa butter is explained firstly by the value of the noble fat with its distinct aroma which, when filtered and purified is similar to best fresh butter in appearance, but is significantly harder. In the finished chocolate, it has a great share in the structure, gloss and the pleasant melt. Although cocoa butter is traded in great style, single-variety cocoa butter is hardly obtainable on the market at all. In principle, in processes for obtaining cocoa butter, there is always interest in the maximum yield of the liquid cocoa butter phase. In the process for defatting the cocoa mass, the focus correspondingly lies on the maximum yield of the dry phase.
Depending on what chocolate variety is to be produced, in the subsequent process steps the ingredients and their quantitative fractions are selected according to certain base recipes and they are added in a defined sequence.
On a national or regional level, appropriate acts and regulations establish precisely in what limits the blending ratios may vary and what ingredients may be used.
For producing dark chocolate having a high cocoa content, generally, according to the base recipe, cocoa mass, cocoa butter, cocoa powder, sugar and vanilla or vanillin are used. These ingredients are finely divided and kneaded in a mixer until a homogeneous pasty mass has formed which, however, is perceived as sandy, since the cocoa particles and the sugar are still present at a size in the range from 20 to 500 μm. In addition, the mass still contains a number of unwanted constituents which adversely effect the flavour.
In order to optimize the sensory properties, the mass is comminuted in a roll mill under the action of pressure and shear forces down to a particle size of below 20 μm.
The odour and flavour substances which are unwanted and disadvantageous for the aroma of the chocolate, which are present, for example, as volatile acids, and which are still present in the roll-milled mass, are removed in the subsequent conching. The intensive shear and friction forces (internal friction) and the intense aeration to which the roll-milled mass is exposed during conching contribute critically to the improvement in taste and sensory properties of the chocolate. In earlier times, conching was performed for up to several days. Thanks to modern conching processes, the processing time in modern turnover conchees can be reduced to a few hours. Nevertheless this ensures that the highest homogeneity and smoothness are achieved, and the individual components of the chocolate are bound together in flavour. A fine film of cocoa butter deposits around each of the microscopically small sugar and cocoa particles.
After completion of conching, the liquid chocolate mass can be stored temporarily at 45 to 50° C. Immediately before the moulding process it is precrystallized. The precrystallization also called tempering, is a critical process since it is responsible for the soft melt, the silky gloss and the rounded flavour of the solidified chocolate. In addition, it plays an important role for the storage life of the finished chocolate. The dark chocolate mass, during the precrystallization, is warmed with gentle movement to 50° C., then cooled to about 27 to 29° C., and again warmed to about 29 to 32° C. It has then reached the correct flow property and crystallization precursor, and so, after pouring into the moulds and solidification, problem-free removal from the moulds is guaranteed.
According to the known production processes for dark chocolates having a high cocoa content, cocoa powder must be added in the mixer, since the cocoa mass having a customary fat content of greater than 50% by weight cannot be further processed using rolls. If a high cocoa content must be achieved, the fat content may only be reduced to a certain extent by adding sugar, and so efficient rolling is only possible after addition of cocoa powder.